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분류없음2011.06.08 15:43
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2011/06/07 - [분류 전체보기] - 미국, 2007년 한국서 고농축우라늄 4파운드 회수
2011/06/08 - [분류 전체보기] - 김효재 정무수석내정자- 김두우 홍보수석내정자 재산신고 내역 [2011년기준]
2011/06/08 - [분류 전체보기] - 박사과정 한인여성 박지혜씨, GPS이용 지하핵실험탐지법개발 - 북한핵실험탐지통해 입증: 내일 CTBTO서 발표
2011/06/08 - [분류 전체보기] - 김효재의원-김두우기획관 병역사항 - 병무청조회


GPS기술을 이용해 지하핵실험을 탐지하는 새로운 방법이 박사과정에 재학중인 한인여성과학자를 통해 개발돼 전세계적 관심을 불러 일으키고 있습니다

오하이오주립대학교 측지학과[GEODETIC] 박사과정에 재학중인 여성과학자 박지혜씨가 현지시간 내일[9일]
오후 오스트리아 빈에서 포괄적 핵실험 금지조약기구 [CTBTO;Comprehensive Nuclear-Test-Ban Treaty Organization ]총회뒤 열리는 세미나에서 GPS기술을 이용해 지하핵실험 장소와 시간을 탐지하는 새로운 방법을 발표할 것이라고 CTBTO가 전했습니다 

또 오하이오주립대학교도 이같은 내용의 보도자료를 웹사이트에 올렸습니다  

박지혜씨는 '전리층탐사를 통한 북한지하핵실험 탐지'[Ionospheric detection of the recent North Korean underground nuclear test]라는 논문발표를 통해 지하핵실험때 전리층의 이온밀도변화를 GPS용 위성을 통해 감지해 지하핵실험 시간과 장소를 탐지하는 방법을 개발했으며 지난 2009년 5월 북한 2차 핵실험당시 한국등 11개 GPS 스테이션에서 감지한 데이터를 입수, 이를 입증했습니다

현재 지하핵실험 감지 방법은 지진탐지, 음향탐지, 대기중 방사능측정등을 통한 방법이 있으나 GPS를 이용한 방법은 전혀 새로운 기술입니다 

박지혜씨는 지난 2009년 북한 핵실험 당일의 GPS 데이터를 한국 6개등 모두 11개 GPS 스테이션에서 입수, 분석한 결과 핵실험순간에 전리층 이온밀도에 급격한 스파이크가 발생했고 핵실험시간이 UTC기준 새벽1시 였던 것으로 드러났다며 이는 지진계등 기존방식을 통한 핵실험탐지에서 드러난 정보와 일치한다고 밝혔습니다

특히 북한 핵실험지역에서 225마일 떨어진 강원도의 GPS스테이션에는 약 25분뒤 이같은 신호가 감지됐으며 
따라서 이 전리층 이온밀도변화는 분당 9마일, 시간당 540마일의 속도로 이동, GPS용 위성에 탐지된다고 전했습니다

박지혜씨의 박사과정 지도교수인 랄프 본 프리즈박사는 '이같은 발견은 지하핵실험 탐지방법의 새로운 장을 열었을 뿐 아니라 지하핵실험이 전리층에 까지 영향을 미친다는 것을 입증한 것'으로 평가했습니다

박지혜씨는 GPS시그널과 전리층 이온밀도를 수치화하는 독특한 알고리즘을 독자적으로 개발, 이같은 탐지방법을 
수립했습니다 

박지혜씨는 내일[9일] 오후 2시 30분, 오스트리아 빈에서 열리는 CTBTO 총회에 이어서 개최되는 세미나에서 이같은 혁신적 지하핵실험 탐지방법을 발표하게 됩니다 
 
http://www.ctbto.org/specials/ctbt-science-and-technology-20118-10-june-2011-vienna-austria/

http://researchnews.osu.edu/archive/gpsnukes.htm
 

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GPS STATIONS CAN DETECT CLANDESTINE NUCLEAR TESTS

VIENNNA, Austria – At the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) meeting this week, American researchers are unveiling a new tool for detecting illegal nuclear explosions: the Earth’s global positioning system (GPS).

Even underground nuclear tests leave their mark on the part of the upper atmosphere known as the ionosphere, the researchers discovered, when they examined GPS data recorded the same day as a North Korean nuclear test in 2009. Within minutes on that day, GPS stations in nearby countries registered a change in ionospheric electron density, as a bubble of disturbed particles spread out from the test site and across the planet.

“Its as if the shockwave from the underground explosion caused the earth to ‘punch up’ into the atmosphere, creating another shockwave that pushed the air away from ground zero,” said Ralph von Frese, professor of earth sciences at Ohio State University and senior author on the study.

Ralph von Frese

Jihye Park, a doctoral student in geodetic science at the university, is presenting the results of the study this Wednesday, Thursday, and Friday in a poster session at the CTBTO meeting in Vienna, Austria.

International authorities already possess several methods for detecting illegal nuclear tests, Park said. Seismic detectors pick up shockwaves through land, and acoustic sensors monitor for shockwaves through water and the air for tests that happen above ground.  Chemical sensors detect airborne radioactive gas and dust as definitive evidence of a nuclear explosion.  However, these particles may be lacking if the explosion is contained deeply below ground.  

“GPS is a complement to these other methods, and can help confirm that a nuclear test has taken place – especially when the test was underground, so that its effect in the air is very subtle, and otherwise nearly impossible to detect,” she said.

While GPS was designed for location purposes, the technology has always been especially sensitive to atmospheric disturbances, said Dorota Grejner-Brzezinska, a professor of geodetic science at Ohio State and Park’s advisor.

“GPS signals must pass from transmitters on satellites high above the planet down to ground-based receivers,” Grejner-Brzezinska explained. “Air molecules – more specifically, the electrons and other charged particles in the ionosphere – interfere with the signal, generating position error. Part of our research concerns how to compensate for that vulnerability and make GPS work better. Jihye found a way to take that vulnerability and turn it into something useful.”

Park wrote computer algorithms that search GPS signals for patterns indicating a sudden fluctuation in atmospheric electron density in specific locations, which is what happens when a shockwave pushes a bubble of air through the atmosphere. As the GPS signal passes through the edge of the bubble, the change in electron density disturbs the signal in a noticeable way.

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Based on the timing of the shockwave, the researchers traced the origin of the explosion back to P’unggye, in Hamyong Province, North Korea. This finding agrees with seismic data from the event, which was collected by the CTBTO and the US Geological Survey.


Park was able to utilize data collected from GPS receivers that the International GNSS Service (IGS) has planted around the globe for research purposes. Five of the IGS receivers scattered in Eastern Asia provided data for this study, as did six receivers belonging to the South Korean GPS network.

When Park analyzed the data from the 11 GPS stations, she detected a sudden spike in atmospheric electron density after the May 25, 2009 underground test, which is believed to have happened just before 1:00 a.m. Coordinated Universal Time that day.

Within 25 minutes, the shockwave had traveled 225 miles to the nearest GPS station in the study, which was located in Inje County, in Gangwon Province, South Korea. That means that it was traveling through the air at 9 miles per minute, or 540 miles per hour. Within that first hour, it had reached all 11 stations.

Based on the timing of the shockwave, the researchers traced the origin of the explosion back to P’unggye, in Hamyong Province, North Korea. This finding agrees with seismic data from the event, which was collected by the CTBTO and the US Geological Survey.

The researchers will continue this work as Park earns her PhD, and they are seeking funding and partnerships to expand it further. In the meantime, they have submitted a paper on the discovery to the journal Geophysical Research Letters.

Collaborators on the study include Yu Morton, professor of electrical and computer engineering at Miami University in Oxford, Ohio, and Luis Gaya-Pique of CTBTO’s On-Site Inspection Division.

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Ralph von Frese, (614) 292-5635; Von-frese.3@osu.edu
Dorota Grejner-Brzezinska; DBrzezinska@osu.edu
Jihye Park; Park.898@osu.edu

Written by Pam Frost Gorder, (614) 292-9475; Gorder.1@osu.edu
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